Singh, lawyer of two convicts, Pawan and Vinay told ANI he is hopeful that his clients would get justice.
It all started on the fateful day of December 16, 2012, when the four appellants along with the main accused late Ram Singh and the juvenile accused took out a bus for a "joyride" as was the routine on Sunday evenings. The case triggered angry protests by thousands of people as well as soul-searching about the country's treatment of women.
Earlier this year, the issue of women's safety erupted again after an 8-year-old Muslim girl was gang-raped and killed in the northern state of Jammu & Kashmir and a lawmaker from the governing Bharatiya Janata Party was arrested and charged with raping a teenager.More news: Sen Claims Dems Would Block George Washington for Supreme Court
The fourth did not appeal, but his lawyer said they would soon file one, according to the Press Trust of India news agency.
A 17-year-old also involved was sentenced to three years in a detention centre and has since been released. Challenging the Supreme Court's verdict, Mukesh had past year filed a review petition alleging that the court had not properly examined crucial evidence in the case.
Following the 2012 case and subsequent protests, some of which were violent, there were demands to overhaul the laws on sexual assaults.
According to National Crime Records Bureau data for 2016, incidents of rape of children in India increased by over 82 percent compared with 2015, when almost 35,000 rape cases were reported to the police.More news: Leckie named a 'breakout star' of the World Cup
The girl from the northern Jammu region died after being kidnapped, drugged and gang raped by several men for days at a Hindu temple. On July 9, 2018 SC will decide the fate of the four accused of death sentence in the Nirbhaya gang-rape case.
"There is absolutely no link between death sentence and deterrence of crime".
India rejected a 2007 United Nations sponsored moratorium plea on executions amid an ongoing debate on capital punishment. "Instead, the government must allocate adequate resources for the effective implementation of laws, improve conviction rates and ensure certainty of justice in all cases", Asmita Basu, Amnesty International India's Programmes director, said.
But many were spared the noose by higher courts on appeals, including 35 who were acquitted outright.More news: 'Fallout Shelter' On Switch A Success, But Don't Expect 'Skyrim' Mods
The three other hangings - in 2010, 2011 and 2015 - were for terrorism.